Production of L-serine by the methanol utilizing bacterium, Pseudomonas 3ab

Abstract

A bacterium capable of growth on methanol and some organic acids as sole source of carbon and energy has been isolated and designated Pseudomonas 3ab. This facultative methylotrophic organism apparently utilizes the serine pathway of formaldehyde fixation. When methanol was used as the sole carbon source for growth, L-serine production by Pseudomonas 3ab occurred upon the addition of glycine and methanol at the end of the exponential growth phase. The maximum yield of L-serine (4.7 g/l) was obtained when 20 g/l glycine and 8 g/l methanol were added and the pH of the culture medium was changed to 8.5. Although Pseudomonas 3ab is unable to grow on L-serine or glycine, it is very active in decomposing these amino acids. The degradation of L-serine and glycine has been shown to be pH-dependent with a minimum at pH 8.5–9.0.